Air conditioner

ABSTRACT

Provided is an air conditioner. The air conditioner including a compressor for compressing a refrigerant, a condenser for condensing the refrigerant compressed by the compressor, a phase separator for separating a gaseous refrigerant from the refrigerant passing through the condenser, and an evaporator for evaporating the refrigerant passing through the phase separator includes an inflow part provided in the phase separator to introduce the refrigerant into the phase separator, a gas separation part configured to discharge the gaseous refrigerant separated by the phase separator, an injection passage configured to inject the refrigerant discharged from the phase separator into the compressor, and an internal heat-exchanger provided within the phase separator to heat-exchange a refrigerant therein with the refrigerant introduced through the inflow part.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. 119 and 35U.S.C. 365 to Korean Patent Application No. 10-2001-0089982 filed onSep. 6, 2001, which is hereby incorporated by reference in its entirety.

BACKGROUND

The present disclosure relates to an air conditioner, and moreparticularly, to an air conditioner having improved system efficiencyand performance and a compact size.

Generally, an air conditioner is an appliance that cools and heats anindoor space by heat-exchanging between air and a refrigerant while therefrigerant is compressed, condensed, expanded, and evaporated. The airconditioner includes a compressor, a condenser, an expansion valve, andan evaporator. The refrigerant discharged from the compressor iscondensed in the condenser and expanded in the expansion valve. Theexpanded refrigerant is evaporated in the evaporator and then is suckedagain into the compressor.

However, the air conditioner according to a related art may notsufficiently execute its cooling or heating performance when a coolingor heating load is varied according to variations of temperatures ofindoor and outdoor spaces. For example, in case of an extreme cold area,since a temperature exchange with external air does not smoothly occur,the cooling performance may be significantly deteriorated. To solve thislimitation, a compressor having large capacity should be provided or anadditional compressor should be further provided.

To solve the above-described limitation, a vapor injection method forreducing a load of the compressor and securing a sufficient refrigerantby introducing a portion of the refrigerant passing through thecondenser again into the compressor when the cooling or heating load isincreased has been proposed.

Referring to FIG. 1, the air conditioner according to the related artincludes a compressor 10 including a first compression part 12, a secondcompression part 14, and a third compression part 16.

A refrigerant discharged from the compressor 10 passes through a firstexpansion unit 30 via a condenser 20. The refrigerant passing throughthe first expansion unit 30 inflows into a phase separator 40. Therefrigerant inflowing into the phase separator 40 is in a state in whicha liquid refrigerant and a gaseous refrigerant are mixed with eachother, and also is separated into the liquid refrigerant and the gaseousrefrigerant by passing through the phase separator 40. The phaseseparator 40 discharges the separated gaseous refrigerant into aseparate tube. Also, the refrigerating in which the liquid refrigerantremaining after the gaseous refrigerant is separated and the gaseousrefrigerant are mixed with each other are discharged through a separateoutflow part.

The separated gaseous refrigerant may flow toward a discharge part ofthe second compression part 14 of the compressor 10 through a firstinjection tube 45. The refrigerant discharged from the secondcompression part 14 and the refrigerant introduced through the firstinjection tube 45 are mixed with each other to flow into the thirdcompression part 16.

A first injection valve 42 is disposed in the first injection tube 45.The first injection valve 42 may control the amount of refrigerantflowing into the first injection tube 45 according to a heating load ofthe air conditioner.

The liquid and gaseous refrigerants discharged from the phase separator40 flow into an internal heat-exchanger 50. The air conditioner mayfurther include a second injection tube branched from a tube connectedto the internal heat-exchanger 50. The refrigerant flowing into thesecond injection tube 65 may be heat-exchanged with the refrigerantdischarged from the phase separator 40 while flowing into the internalheat-exchanger 50.

The second injection tube 65 is connected to the compressor 10. Indetail, the second injection tube 65 is connected to the discharge partof the first compression part 12. Also, the refrigerant flowing into thesecond injection tube 65 is mixed with the refrigerant discharged fromthe first compression 12, and then the mixed refrigerant flows into thesecond compression part 14.

The refrigerant discharged from the phase separator 40 is throttledwhile passing through a second expansion valve 70, and the refrigerantpassing through the second expansion valve 70 flows into an evaporator80. The refrigerant evaporated in the evaporator 80 is introduced againinto the compressor 10 to form a heating cycle.

As described above, in the air conditioner according to the related art,to inject the refrigerant into the compressor 10 including the pluralityof compression parts, the phase separator 40 and the internalheat-exchanger should be separately provided. Thus, the air conditionermay be complicated in structure and increased in manufacturing cost.

Although not shown, the phase separator 40 may be omitted and theinternal heat-exchanger may be provided. In this case, the refrigerantmay be injected into the compressor using two internal heat-exchangers.Similarly, in case where the two internal heat-exchangers are provided,the air conditioner may be complicated in structure and increased inmanufacturing cost.

SUMMARY

Embodiments provide an air conditioner which is capable of improvingcooling or heating performance and efficiently utilizing an inner space.

Embodiments also provide an air conditioner including an internalheat-exchanger and a phase separator which are capable of being utilizedduring the cooling or heating.

In one embodiment, an air conditioner including a compressor forcompressing a refrigerant, a condenser for condensing the refrigerantcompressed by the compressor, a phase separator for separating a gaseousrefrigerant from the refrigerant passing through the condenser, and anevaporator for evaporating the refrigerant passing through the phaseseparator includes: an inflow part provided in the phase separator tointroduce the refrigerant into the phase separator; a gas separationpart configured to discharge the gaseous refrigerant separated by thephase separator; an injection passage configured to inject therefrigerant discharged from the phase separator into the compressor; andan internal heat-exchanger provided within the phase separator toheat-exchange a refrigerant therein with the refrigerant introducedthrough the inflow part.

In another embodiment, an air conditioner includes: a multi-stagecompressible compressor; a phase separator for separating a gaseousrefrigerant from a liquid refrigerant; a gas separation part configuredto discharge the gaseous refrigerant separated by the phase separator,the gas separation part guiding injection of the refrigerant into thecompressor; an inflow part configured to introduce the refrigerant intothe phase separator; an outflow part configured to discharge therefrigerant introduced through the inflow part; a bypass part branchedfrom the outflow part to guide the inflow of the refrigerant into thephase separator; and an internal heat-exchanger configured toheat-exchange the refrigerant stored in the phase separator with therefrigerant flowing into the bypass part.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features will be apparent fromthe description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating a refrigerant cycle of an airconditioner according to a related art.

FIG. 2 is a view of a phase separator according to an embodiment.

FIG. 3 is a view illustrating a connection relationship between a phaseseparator and a compressor according to an embodiment.

FIG. 4 is a view illustrating a refrigerant flow during the heating in arefrigerant cycle in which a phase separator is applied according to anembodiment.

FIG. 5 is a view illustrating a refrigerant flow during the cooling in arefrigerant cycle in which a phase separator is applied according to anembodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, exemplary embodiments will be described with reference tothe accompanying drawings. The invention may, however, be embodied inmany different forms and should not be construed as being limited to theembodiments set forth herein; rather, that alternate embodimentsincluded in other retrogressive inventions or falling within the spiritand scope of the present disclosure will fully convey the concept of theinvention to those skilled in the art.

In the detailed description of the present application, a term an “inletside” or “outlet side” may a term defined based on a flow direction of arefrigerant.

FIG. 2 is a view of a phase separator according to an embodiment. FIG. 3is a view illustrating a connection relationship between a phaseseparator and a compressor according to an embodiment.

Referring to FIGS. 2 and 3, an air conditioner according to anembodiment includes a compressor 200 and a phase separator 100 fordischarging a refrigerant to be injected into the compressor 200.

In detail, the compressor 200 includes first, second, and thirdcompression parts 202, 204, and 206 to compress the refrigerant inmultiple stages. Thus, the refrigerant flowing into the compressor 200is compressed while successively passing through the first, second, andthird compression parts 202, 204, and 206. After the refrigerant iscompressed by the third compression part 206, the refrigerant isdischarged from the compressor 10.

The phase separator 100 includes an inflow part 110 through which arefrigerant expanded through a first expansion unit 210, a gasseparation part 130 through which a gaseous refrigerant separated fromthe refrigerant flowing into the inflow part 110 is discharged, and anoutflow part 120 through which the refrigerant flowing into the inflowpart 110 and remaining after the gaseous refrigerant is separated isdischarged.

The first expansion unit 210 decompresses the refrigerant condensed by acondenser. The refrigerant has a two-phase state, i.e., a state in whichthe liquid refrigerant and the gaseous refrigerant are mixed with eachother when the refrigerant is decompressed by the first expansion unit210.

The gaseous refrigerant of the refrigerant introduced through the inflowpart 110 is discharged through the gas separation part 130. To easilydischarge the gaseous refrigerant, the gas separation part 130 extendsupward from a top surface of the phase separator 100.

A high pressure injection passage 235 for guiding the gaseousrefrigerant discharged from the gas separation part 130 to thecompressor 200 is disposed between the gas separation part 130 and thecompressor 200.

The high pressure injection passage 235 is connected to a discharge sideof the second compression part 204. The refrigerant flowing into thehigh pressure injection passage 235 is mixed with the refrigerantcompressed by the second compression part 204 and flows into the thirdcompression pat 206. A portion of the compressor 200 connected to thehigh pressure injection passage 235 may be called a “high pressurepart”.

An injection valve 230 for adjusting the amount of refrigerant to beinjected into the compressor 200 is disposed in the high pressureinjection passage 235. An opening degree of the injection valve 230 maybe controlled based on the amount of refrigerant required according tothe cooling or heating load.

The refrigerant introduced through the inflow part 110 is cooled whenthe refrigerant is heat-exchanged in an internal heat-exchanger 145 andthen discharged to the outside of the phase separator 100 through theoutflow part 120.

A second expansion unit 220 for decompressing the refrigerant isdisposed at the discharge side of the inflow part 120. The refrigerantdischarged through the inflow part 120 flows into an evaporator afterthe refrigerant is expanded by the second expansion unit 220.

The phase separator 100 includes a first inflow tube 140 through whichat least one portion of the refrigerant discharged through the outflowpart 120 is branched and flows and a first outflow tube 150 for guidingthe refrigerant introduced through the first inflow tube 140 to theoutside of the phase separator 100.

The first inflow tube 140 bypasses the refrigerant discharged from thephase separator 100 to flow again into the phase separator 100. Thus,the first inflow tube 140 may be called a “bypass part”. Also, the firstinflow tube 140 may extend inward from the outside of the phaseseparator 100.

A third expansion unit 240 for expanding the refrigerant is disposed inthe first inflow tube 140. The refrigerant bypassed into the firstinflow tube 140 may be cooled while passing through the third expansionunit 240 and flow into the phase separator 100.

The internal heat-exchanger 145 communicating with the first inflow tube140 and the first outflow tube 150 is disposed in an inner space of thephase separator 100. The refrigerant introduced through the first inflowtube 140 flows into the first outflow tube 150 via the internalheat-exchanger 145.

The internal heat-exchanger 145 may have a structure which includes atube through which a refrigerant flows and has a wide surface area toimprove heat-exchange efficiency. For example, the internalheat-exchanger 145 may have a plurality of bent shapes such as a coil.

The refrigerant (hereinafter, referred to as a first refrigerant)introduced through the inflow part 110 and the refrigerant (hereinafter,referred to as a second refrigerant) introduced through the first inflowtube 140 are heat-exchanged with each other in the internalheat-exchanger 145. In detail, the refrigerant introduced through theinflow part 110 is disposed at the outside of the tube of the internalheat-exchanger 145 in a state where the refrigerant is stored in thephase separator 100. Also, the refrigerant introduced through the firstinflow tube 140 flows into the tube. Thus, the refrigerants may beheat-exchanged with each other.

When the first and second refrigerants are heat-exchanged with eachother, the second refrigerant absorbs heat. As a result, at least oneportion of the second refrigerant may be phase-changed in a gaseousstate. The phase-changed gaseous refrigerant is discharged to theoutside of the phase separator 100 through the first outflow tube 150.The first outflow tube 150 extends upward from the top surface of thephase separator 100.

A low pressure injection passage 250 for guiding the refrigerantdischarged through the first outflow tube 150 to the compressor 200 isdisposed between the phase separator 100 and the compressor 200. The lowpressure injection passage 250 is connected to a discharge side of thefirst compression part 202. The refrigerant flowing into the compressor200 through the low pressure injection passage 250 may be mixed with therefrigerant compressed by the first compression part 202 and flow intothe second compression part 204.

A portion of the compressor 200 connected to the low pressure injectionpassage 250 may be called a “low pressure part”. The refrigerant flowinginto the low pressure injection passage 250 may have a pressure lessthan that of the refrigerant flowing into the high pressure injectionpassage 235.

The amount of refrigerant injected through the low pressure injectionpassage 250 may be adjusted by controlling an opening degree of thethird expansion unit 240. The opening degree of the third expansion unit240 may be adjusted based on the amount of refrigerant introducedthrough the inflow part 110 or a state of the refrigerant.

That is, since the heat-exchanged amount or heat-exchange efficiency inthe internal heat-exchanger 145 may be determined according to theamount (or the stored refrigerant amount) of refrigerant stored in thephase separator 100 or a state of the refrigerant, the amount ofrefrigerant to be injected into the compressor 200 may be adjustedaccording to the stored refrigerant amount.

A refrigerant flow will be described below.

The refrigerant decompressed by the first expansion unit 210 is storedin the phase separator 100 through the inflow part 110 andheat-exchanged with the refrigerant flowing into the internalheat-exchanger 145. Then, the refrigerant is discharged through theoutflow part 120. The refrigerant discharged through the outflow part120 is decompressed by the second expansion unit 220 and flows into theevaporator.

At least one portion of the refrigerant discharged through the outflowpart 120 is expanded by the second expansion unit 240 and then flowsinto the phase separator 100 through the first inflow tube 140. Also,the refrigerant of the first inflow tube 140 flows into the internalheat-exchanger 145 and heat-exchanged with the refrigerant stored in thephase separator 100. Then, the refrigerant is discharged to the outsideof the phase separator 100 through the first outflow tube 150.

The refrigerant discharged through the first outflow tube 150 flows intothe low pressure part of the compressor 200 through the low pressureinjection passage 250.

The gaseous refrigerant of the two-phase refrigerant stored in the phaseseparator 100 is discharged through the gas separation part 130 andinjected into the high pressure part of the compressor 200.

As described above, the refrigerant may be injected into the compressor200 through the plurality of injection passages 235 and 250 to secure asufficient refrigerant even though the heating load is large. Also, arefrigerant having a middle pressure may flow to reduce an operationload of the compressor 200. Here, the middle pressure may be greaterthan a suction pressure of the compressor 200 and less than a dischargepressure of the compressor 200.

FIG. 4 is a view illustrating a refrigerant flow during the heating in arefrigerant cycle in which a phase separator is applied according to anembodiment. FIG. 5 is a view illustrating a refrigerant flow during thecooling in a refrigerant cycle in which a phase separator is appliedaccording to an embodiment.

A refrigerant cycle of the air conditioner will be described withreference to FIG. 4. The air conditioner may include a four-way valve320 for adjusting a flow direction of the refrigerant discharged fromthe compressor 200 according to a cooling or heating operation, anoutdoor heat-exchanger 330 in which indoor air is heat-exchanged withoutdoor air in an indoor room, and an accumulator 350 for temporarilystoring the refrigerant flowing into the compression 200.

A refrigerant passing through the condenser flows into the phaseseparator 100 via the first expansion unit 210. In detail, when the airconditioner is operated in the cooling mode, the refrigerant passingthrough the outdoor heat-exchanger 330 may flow into the phase separator100. Also, when the air conditioner is operated in the heating mode, therefrigerant passing through the indoor heat-exchanger 340 may flow intothe phase separator 100.

The air conditioner may further include a plurality of check valves anda plurality of connection passages which adjust the refrigerant flow sothat the phase separation and the refrigerant injection into thecompressor are realized during the cooling operation or the heatingoperation.

In detail, the air conditioner includes a first connection passage 312connecting the outflow part 120 to the indoor heat-exchanger 340 and afirst check valve 302 provided in the first connection passage 312. Thefirst check valve 302 is disposed in a passage defined between thesecond expansion unit 220 and the indoor heat-exchanger 340 to guide therefrigerant flow in one direction.

The air conditioner further includes a second connection passage 314branched from one point of the passage defined between the first checkvalve 302 and the indoor heat exchanger 340 and communicating with theinflow part 110. A second check valve 304 through which the refrigerantflows only toward the inflow part 110 is disposed in the secondconnection passage 314.

The air conditioner further includes a third connection passage 316through which the refrigerant flows from the outdoor heat-exchanger 330into the inflow part 110. A third check valve 306 through which therefrigerant flows from the outdoor heat-exchanger 330 into the inflowpart 110 is disposed in the third connection passage 316.

The air conditioner further includes a fourth connection passage 318branched from one point of the passage defined between the first checkvalve 302 and the second expansion unit 220 and communicating with thethird connection passage 316. A fourth check valve 308 through which therefrigerant flows from the first connection passage 312 into the thirdconnection passage 316 is disposed in the fourth connection passage 318.

A refrigerant flow in a refrigerant cycle when the air conditioner isoperated in the heating mode will be described with reference to FIG. 4.

The refrigerant compressed by the compressor 200 flows into the indoorheat-exchanger 340 via the four-way valve 320. The refrigerant condensedin the indoor heat-exchanger flows into the second connection passage314. Here, the first check valve 302 prevents the refrigerant fromflowing into the first connection passage 312.

The refrigerant flowing into the second connection passage 314 isexpanded by the first expansion unit 210 via the second check valve 304.The refrigerant passing through the first expansion unit 210 flows intothe phase separator 100 through the inflow part 110.

The gaseous refrigerant separated by the phase separator 100 is injectedinto the high pressure part of the compressor 200 through the highpressure injection passage 235. The amount of refrigerant to be injectedinto the high pressure part may be adjusted by the injection valve 230,and an opening degree of the injection valve 230 of the injection valve230 may be adjusted according to a heating load. For example, when theheating load is large, the opening degree of the injection valve 230 maybe increased.

The gaseous and liquid refrigerants remaining in the phase separator 100without being separated is discharged through the outflow part 120. Atleast one portion of the refrigerant discharged through the outflow part120 is bypassed into the first inflow tube 140 to flow into the phaseseparator 100. Then, the refrigerant is heat-exchanged with therefrigerant stored in the phase separator 100 in the internalheat-exchanger 145.

The refrigerant heated in the internal heat-exchanger 145 is injectedinto the low pressure part of the compressor 200 through the lowpressure injection passage 250. The amount of refrigerant injected intothe low pressure part may be adjusted by the third expansion unit 240.An opening degree of the third expansion unit 240 may be adjustedaccording to a heating load. For example, when the heating load islarge, the opening degree of the third expansion unit 240 may beincreased.

The refrigerant discharged through the outflow part 120 is expanded bythe second expansion unit 220 to flow into the fourth connection passage318.

The refrigerant may flow from the first connection passage 312 into theindoor heat-exchanger 340 by the first check valve 302. However, sincethe refrigerant discharged from the indoor heat-exchanger 340 has apressure greater than that of the refrigerant of an inlet side of thefirst check valve 302, the refrigerant passing through the secondexpansion unit 220 may flow into the fourth connection passage 318.

The refrigerant passing through the fourth check valve 308 flows intothe outdoor heat-exchanger 330 through the third connection passage 316.

The refrigerant may flow from the third connection passage 316 into theinflow part 110 by the third check valve 306. However, since therefrigerant of an inflow part side has a pressure greater than that ofthe inlet side of the outdoor heat-exchanger 330, the refrigerant mayflow into the outdoor heat-exchanger 330 via the fourth expansion unit308 and the third connection passage 316.

The refrigerant is evaporated in the outdoor heat-exchanger 330, and therefrigerant passing through the outdoor heat-exchanger 330 flows intothe accumulator 350 via the four-way valve 320. The gaseous refrigerantof the refrigerant stored in the accumulator 350 flows into thecompressor 200. This refrigerant cycle may be repeatedly performed.

A refrigerant flow in a refrigerant cycle when the air conditioner isoperated in the cooling mode will be described with reference to FIG. 5.

The refrigerant compressed by the compressor 200 flows into the outdoorheat-exchanger 330 via the four-way valve 320. The condensed refrigerantpassing through the outdoor heat-exchanger 330 flows into the thirdconnection passage 316. The refrigerant flowing into the thirdconnection passage 316 flows into the inflow part 110 via the thirdcheck valve 306 and the first expansion unit 210.

The refrigerant flowing into the third connection passage 316 does notflow into the second connection passage 314 and the fourth connectionpassage 318 by the fourth check valve 308, respectively.

The refrigerant flowing into the inflow part 110 passes through thephase separator 100. Since a flow of the refrigerant injected from thephase separator 100 into the compressor 200 is equal to that of FIG. 4,its description will be omitted.

The refrigerant discharged from the outflow part 150 flows into thefirst connection passage 312 via the second expansion unit 220 and flowsinto the indoor heat-exchanger 340 via the first check valve 302.

Since the refrigerant flowing into the third connection part 316 has apressure greater than that of the refrigerant flowing into the firstconnection passage 312, the inflow of the refrigerant into the secondconnection passage 314 and the fourth connection passage 318 may belimited. The refrigerant passing through the first connection passage312 flows into the indoor heat-exchanger 340.

The refrigerant evaporated in the indoor heat-exchanger 340 flows intothe accumulator 350 via the four-way valve 320. The gaseous refrigerantof the refrigerant stored in the accumulator 350 flows into thecompressor 200. This refrigerant cycle may be repeatedly performed.

According to the proposed embodiment, since the refrigerant is injectedinto the compressor including the multiple stage compression parts, thecirculation amount of refrigerant may be increased to improve thecooling or heating performance.

Also, the internal heat-exchanger may be disposed within the phaseseparator to improve the gas and liquid separation performance. Also,since the phase separator and the internal heat-exchanger may not beseparately provided, the assembly of the air conditioner may be improvedand also the compact air conditioner may be realized.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

1. An air conditioner comprising a compressor for compressing arefrigerant, a condenser for condensing the refrigerant compressed bythe compressor, a phase separator for separating a gaseous refrigerantfrom the refrigerant passing through the condenser, and an evaporatorfor evaporating the refrigerant passing through the phase separator, theair conditioner comprising: an inflow part provided in the phaseseparator to introduce the refrigerant into the phase separator; a gasseparation part configured to discharge the gaseous refrigerantseparated by the phase separator; an injection passage configured toinject the refrigerant discharged from the phase separator into thecompressor; and an internal heat-exchanger provided within the phaseseparator to heat-exchange a refrigerant therein with the refrigerantintroduced through the inflow part.
 2. The air conditioner according toclaim 1, further comprising: an outflow part provided in the phaseseparator to discharge the refrigerant introduced through the inflowpart after the refrigerant introduced through the inflow part isheat-exchanged with the refrigerant within the internal heat-exchanger.3. The air conditioner according to claim 2, further comprising: a firstinflow tube bypassing the refrigerant discharged from the outflow partto introduce the discharged refrigerant into the phase separator; and afirst outflow tube discharging the refrigerant introduced through thefirst inflow tube to the outside of the phase separator.
 4. The airconditioner according to claim 3, wherein the first inflow tube and thefirst outflow tube communicate with the internal heat-exchanger.
 5. Theair conditioner according to claim 3, wherein the refrigerant introducedthrough the first inflow tube flows into the internal heat-exchanger andis heat-exchanged with the refrigerant introduced through the inflowpart.
 6. The air conditioner according to claim 3, wherein the injectionpassage comprises a low pressure injection passage for guiding therefrigerant discharged through the first outflow tube so that therefrigerant is injected into a low pressure part of the compressor. 7.The air conditioner according to claim 6, wherein the injection passagecomprises a high pressure injection passage for guiding the refrigerantdischarged through the gas separation part so that the refrigerant isinjected into a high pressure part of the compressor.
 8. The airconditioner according to claim 7, wherein the compressor comprises afirst compression part for compressing the refrigerant passing throughthe evaporator, a second compression part for compressing therefrigerant compressed by the first compression part, and a thirdcompression part for compressing the refrigerant compressed by thesecond compression part, the refrigerant discharged from the gasseparation part flows into between the second compression part and thethird compression part, and the refrigerant discharged through the firstoutflow tube flows into between the first compression part and thesecond compression part.
 9. The air conditioner according to claim 2,further comprising: a first expansion unit provided at an inlet side ofthe inflow part to expand a refrigerant to be introduced into the phaseseparator; and a second expansion unit provided at an outlet side of theoutflow part to expand a refrigerant.
 10. The air conditioner accordingto claim 3, further comprising: a third expansion unit provided in thefirst inflow tube to expand a refrigerant to be introduced into thephase separator through the first inflow tube.
 11. The air conditioneraccording to claim 2, wherein the condenser or the evaporator is anindoor heat-exchanger, and the air conditioner further comprises: afirst connection passage connecting the outflow part to the indoorheat-exchanger; and a first check valve provided in the first connectionpassage to guide the refrigerant in one direction.
 12. The airconditioner according to claim 11, further comprising: a secondconnection passage branched from one point of a passage defined betweenthe first check valve and the indoor heat-exchanger to communicate withthe inflow part; and a second check valve provided in the secondconnection passage to guide a refrigerant flow in a direction of theinflow part.
 13. The air conditioner according to claim 11, wherein thecondenser or the evaporator is an outdoor heat-exchanger, and the airconditioner further comprises: a third connection passage configured tointroduce a refrigerant from the outdoor heat-exchanger into the inflowpart; and a third check valve provided in the third connection passageto guide the refrigerant flow from the outdoor heat-exchanger toward theinflow part.
 14. The air conditioner according to claim 13, furthercomprising: a fourth connection passage branched from one point of thefirst connection passage to communicate with the third connectionpassage; and a fourth check valve provided in the fourth connectionpassage to introduce a refrigerant from the first connection passagetoward the third connection passage.
 15. An air conditioner comprising:a multi-stage compressible compressor; a phase separator for separatinga gaseous refrigerant from a liquid refrigerant; a gas separation partconfigured to discharge the gaseous refrigerant separated by the phaseseparator, the gas separation part guiding injection of the refrigerantinto the compressor; an inflow part configured to introduce therefrigerant into the phase separator; an outflow part configured todischarge the refrigerant introduced through the inflow part; a bypasspart branched from the outflow part to guide the inflow of therefrigerant into the phase separator; and an internal heat-exchangerconfigured to heat-exchange the refrigerant stored in the phaseseparator with the refrigerant flowing into the bypass part.
 16. The airconditioner according to claim 15, wherein the bypass part is connectedto the internal heat-exchanger, and a first outflow tube for guidingdischarge of the heat-exchanged refrigerant to the outside of the phaseseparator is connected to an outlet side of the internal heat-exchanger.17. The air conditioner according to claim 16, wherein the refrigerantdischarged through the first outflow tube is injected into thecompressor.
 18. The air conditioner according to claim 17, wherein therefrigerant injected from the gas separation part into the compressorhas a pressure greater than that of the refrigerant injected from thefirst outflow tube into the compressor.
 19. The air conditioneraccording to claim 16, wherein at least one of the gas separation partand the first outflow tube extends upward from a top surface of thephase separator.
 20. The air conditioner according to claim 15, furthercomprising: a first expansion unit provided at an inlet side of theinflow part to expand a refrigerant to be introduced into the phaseseparator; a second expansion unit provided at an outlet side of theoutflow part to expand a refrigerant; and a third expansion unitprovided in the bypass part to expand a refrigerant to be introducedinto the phase separator through the bypass part.